The concern for energy conservation has affected all areas of modern living, including conserving the energy used by household major appliances. Heretofore, major appliance dishwashers have freely used hot water indiscriminately, in conjunction with electric heating of air for drying dishes after washing.
Conventionally, dishwashers are connected only to a hot-water line in the kitchen. Thus, all washing and rinsing operations must be done with hot water. An analysis of the energy consumption of a typical dishwasher shows that a major portion of the energy consumed in washing the dishes is the energy used for heating the water and for heating air for drying the dishes. The present invention provides for less energy being used by describing a method of washing dishes utilizing a dishwasher connected to both hot and cold-water lines.
Dishwashers using both hot and cold-water have been suggested by, for example, Stoddard-U.S. Pat. No. 2,825,665. However, Stoddard has failed to recognize one of the fundamental problems of having a dishwasher connected to both hot and cold-water sources. That problem is the thermal shock, caused by exposing dishes to water at a first temperature and, then, water at a second, appreciably different temperature. A severe thermal shock will cause the dishes to break. In addition, Stoddard fails to recognize the advantage of having a cold-water rinse, followed by a hot-water wash, cold-water post-rinse, and then a hot-water rinse. Applicant has, however, overcome the defects of Stoddard in the present invention.